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[PATCH 4.9 14/31] kcm: Fix use-after-free caused by clonned sockets




4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>

[ Upstream commit eb7f54b90bd8f469834c5e86dcf72ebf9a629811 ]

(resend for properly queueing in patchwork)

kcm_clone() creates kernel socket, which does not take net counter.
Thus, the net may die before the socket is completely destructed,
i.e. kcm_exit_net() is executed before kcm_done().

Reported-by: syzbot+5f1a04e374a635efc426@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/kcm/kcmsock.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1671,7 +1671,7 @@ static struct file *kcm_clone(struct soc
 	__module_get(newsock->ops->owner);
 
 	newsk = sk_alloc(sock_net(osock->sk), PF_KCM, GFP_KERNEL,
-			 &kcm_proto, true);
+			 &kcm_proto, false);
 	if (!newsk) {
 		sock_release(newsock);
 		return ERR_PTR(-ENOMEM);